Fix duplicate XT-PIC seen in /proc/interrupts on x86 systems that make
use of 8259A Programmable Interrupt Controllers. Specifically convert
output like this:
CPU0
0: 76573 XT-PIC-XT-PIC timer
1: 11 XT-PIC-XT-PIC i8042
2: 0 XT-PIC-XT-PIC cascade
4: 8 XT-PIC-XT-PIC serial
6: 3 XT-PIC-XT-PIC floppy
7: 0 XT-PIC-XT-PIC parport0
8: 1 XT-PIC-XT-PIC rtc0
10: 448 XT-PIC-XT-PIC fddi0
12: 23 XT-PIC-XT-PIC eth0
14: 2464 XT-PIC-XT-PIC ide0
NMI: 0 Non-maskable interrupts
ERR: 0
to one like this:
CPU0
0: 122033 XT-PIC timer
1: 11 XT-PIC i8042
2: 0 XT-PIC cascade
4: 8 XT-PIC serial
6: 3 XT-PIC floppy
7: 0 XT-PIC parport0
8: 1 XT-PIC rtc0
10: 145 XT-PIC fddi0
12: 31 XT-PIC eth0
14: 2245 XT-PIC ide0
NMI: 0 Non-maskable interrupts
ERR: 0
that is one like we used to have from ~2.2 till it was changed sometime.
The rationale is there is no value in this duplicate information, it
merely clutters output and looks ugly. We only have one handler for
8259A interrupts so there is no need to give it a name separate from the
name already given to irq_chip.
We could define meaningful names for handlers based on bits in the ELCR
register on systems that have it or the value of the LTIM bit we use in
ICW1 otherwise (hardcoded to 0 though with MCA support gone), to tell
edge-triggered and level-triggered inputs apart. While that information
does not affect 8259A interrupt handlers it could help people determine
which lines are shareable and which are not. That is material for a
separate change though.
Any tools that parse /proc/interrupts are supposed not to be affected
since it was many years we used the format this change converts back to.
Signed-off-by: Maciej W. Rozycki <ma...@linux-mips.org>
---
Original report recorded here: https://lkml.org/lkml/2014/9/25/190 --
and given no feedback here is a fix, as promised. I'll be happy to
discuss it further if there is any concern about this change.
Otherwise, please apply.
Maciej
linux-x86-xt-pic.patch
Index: linux-3.16-dolch/arch/x86/kernel/i8259.c
===================================================================
--- linux-3.16-dolch.orig/arch/x86/kernel/i8259.c
+++ linux-3.16-dolch/arch/x86/kernel/i8259.c
@@ -111,8 +111,7 @@ static void make_8259A_irq(unsigned int
{
disable_irq_nosync(irq);
io_apic_irqs &= ~(1<<irq);
- irq_set_chip_and_handler_name(irq, &i8259A_chip, handle_level_irq,
- i8259A_chip.name);
+ irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
enable_irq(irq);
}
Index: linux-3.16-dolch/arch/x86/kernel/irqinit.c
===================================================================
--- linux-3.16-dolch.orig/arch/x86/kernel/irqinit.c
+++ linux-3.16-dolch/arch/x86/kernel/irqinit.c
@@ -70,7 +70,6 @@ int vector_used_by_percpu_irq(unsigned i
void __init init_ISA_irqs(void)
{
struct irq_chip *chip = legacy_pic->chip;
- const char *name = chip->name;
int i;
#if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
@@ -79,7 +78,7 @@ void __init init_ISA_irqs(void)
legacy_pic->init(0);
for (i = 0; i < nr_legacy_irqs(); i++)
- irq_set_chip_and_handler_name(i, chip, handle_level_irq, name);
+ irq_set_chip_and_handler(i, chip, handle_level_irq);
}
void __init init_IRQ(void)
--
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